This research is aimed at gaining an understanding of the neural mechanisms involved in the production of cyclic jaw movement and at gaining an understanding of the mechanisms used to produce the fractionation activity in bilateral pairs of jaw closing muscles which is necessary for the production of lateral jaw movements. Guinea pigs are trained to sit quietly and masticate small pieces of food while jaw movements are monitored using an optically coupled tracking system. Parameters of jaw movement are related to EMG patterns in the jaw closing muscles and to patterns of activity of neurons in several brain centers which might be part of an neural pattern generator for mastication. Lesions and microstimulation of these brain centers are also used to provide information about possible pattern generator activity. Lesions and microstimulation of the face area motor cortex are used to determine the function of this area, particularly in reference to lateral jaw movement. Degeneration stains are used following cortical lesion to determine the subcortical connections of this area cortex.